Data writing devices function to digitally encode and store information. In a writing device employing a rotary actuator, such as a servo writer or a disc drive and the like, data transfer members are supported at the end of thin cantilevered actuator arms that merge into the spaces between adjacent discs in a disc stack. The actuator arms are operably positioned to precisely locate the data transfer members with respect to addressable locations of a storage media.
Some environmental conditions create problems that have been the subject of continual improvement efforts for some time. Cleanliness, for example, has long been known to be important in the process of writing data because of the extremely small space that exists between the data transfer member and the media during writing. A contaminant particle that gets trapped in that space can cause damage to the data transfer member and to the storage media. Windage is another example of an environmental condition creating problems that have continually been the subject of mitigation efforts. The outwardly spiraling windage currents can create perturbations that excite the actuator arm, the head gimbal assembly (HGA) supported by the actuator arm, and the edge of the disc, usually causing non-repeatable displacements of the data transfer member away from the target track.
Other environmental issues are heretofore unrecognized as being a concern because they arise as the result of new constraints brought on by modern levels of data storage areal density. That is, the positioning scrutiny demanded by today's smaller storage track widths means that some sources of variation that were once ignored as negligible must now be confronted. Under these constraints, it has been observed that in some circumstances a spindle motor operably supporting a disc stack can transfer enough thermal energy to the HGAs in the disc stack to produce measurable low frequency DC wander in the HGAs. The magnitude of this thermal excitation and the resulting DC error tends to be transient, and tends to affect discs within the same disc stack differently. The present embodiments are directed to novel solutions to these problems.